WILLIAMSEN CAMPAIGN NO N/A.SDTC AND ADTC END DUMP TRAILERS 1971 THRU 1973.POSSIBILITY THAT THE REAR BOGIE SUBFRAME ASSEMBLY MAY DEVELOP CRACKS.IFCRACKS IN THIS AREA GO UNNOTICED AND ARE NOT REINFORCED, IT IS POSSIBLE FOR THEREAR TANDEM SUSPENSION AS A UNIT WITH THE TWO AXLES, WHEELS AND TIRES TO BREAKLOOSE AND ROLL BACKWARDS FROM THE TRAILER DURING A SEVERE APPLICATION OF THETRAILER BRAKES.(CORRECT BY INSPECTING AND REINFORCING WITH A 1/4" STEELGUSSET WHERE NECESSARY).